1. Field of the Invention
The present general inventive concept relates to a method of managing a simple network management protocol (SNMP), and more particularly, to a system and method to manage a set history for an SNMP.
2. Description of the Related Art
FIG. 1 illustrates a basic communication operation of an SNMP. Referring to FIG. 1, an SNMP manager manages a network through three types of commands: GET commands, SET commands, and TRAP commands. A GET command allows the SNMP manager to retrieve an object ID from an SNMP agent. A SET command allows the SNMP manager to change the object ID of the SNMP agent. A TRAP command informs the SNMP manager of a specific condition in the SNMP agent or in the network. For example, a TRAP command may be a warning or error message transmitted from the SNMP agent to the SNMP manager to notify the SNMP manager about the SNMP agent's condition. Unlike GET and SET commands, TRAP commands are asynchronous and are not solicited by the SNMP manager.
Referring to FIG. 1, the SNMP manager retrieves an object ID from the SNMP agent using a GET-REQUEST command. In addition, the SNMP manager retrieves a further object ID subsequent to the object ID that the SNMP manager has previously-retrieved, or a subsequent index when the object ID is a table, using a GETNEXT-REQUEST command.
When a GET-RESPONSE command is transmitted by the SNMP agent, the SNMP agent returns the object ID corresponding to the request of the SNMP manager. The SNMP manager requests the SNMP agent to change the object ID using a SET-REQUEST command. The SNMP agent reports a specific condition in the SNMP agent to the SNMP manager using a TRAP command.
FIG. 2 is a flowchart illustrating a procedure in which a conventional SNMP manager sets an object ID. In operation 200, the SNMP manager accesses a network apparatus having an SNMP agent and requests the SNMP agent to set a particular object value using a SET-REQUEST command. In operation 210, an SNMP agent sets the object ID according to the SET-REQUEST of the SNMP manager. In operation 220, the SNMP agent transmits set information corresponding to the set object ID to the SNMP manager using a GET-RESPONSE command.
Conventionally, when an SNMP manager changes or sets an object ID of an SNMP agent on a network using a SET-REQUEST command, the SNMP agent transmits the corresponding set information in a GET-RESPONSE command only to that SNMP manager (i.e., only to the SNMP manager that transmitted the SET-REQUEST to the SNMP agent). Other SNMP managers on the network do not receive the GET-RESPONSE command from the SNMP agent, and therefore do not receive the set information. Although, these other SNMP managers on the network can determine a current object value of the SNMP agent (i.e., the set object value based on the SET-REQUEST), these other SNMP managers cannot obtain past set-information (i.e., set information based on previous SET-REQUEST commands by one or more different SNMP managers). For example, when set information such as the name of a network apparatus that is difficult to memorize has been changed by one or more SNMP managers, it is not known what specific SNMP manager set the changed/current name of the network apparatus. Furthermore, even if the specific SNMP manager that set the changed/current name is known, it is inconvenient to return the name from the changed/current name to a past name because a complicated apparatus name must be directly/manually input into the corresponding SNMP agent.